Structural highlights
Publication Abstract from PubMedSmall heat shock proteins (sHsps) are molecular chaperones that prevent the aggregation of nonnative proteins. The sHsps investigated to date mostly form large, oligomeric complexes. The typical bacterial scenario seemed to be a two-component sHsps system of two homologous sHsps, such as the Escherichia coli sHsps IbpA and IbpB. With a view to expand our knowledge on bacterial sHsps, we analyzed the sHsp system of the bacterium Deinococcus radiodurans, which is resistant against various stress conditions. D. radiodurans encodes two sHsps, termed Hsp17.7 and Hsp20.2. Surprisingly, Hsp17.7 forms only chaperone active dimers, although its crystal structure reveals the typical alpha-crystallin fold. In contrast, Hsp20.2 is predominantly a 36mer that dissociates into smaller oligomeric assemblies that bind substrate proteins stably. Whereas Hsp20.2 cooperates with the ATP-dependent bacterial chaperones in their refolding, Hsp17.7 keeps substrates in a refolding-competent state by transient interactions. In summary, we show that these two sHsps are strikingly different in their quaternary structures and chaperone properties, defining a second type of bacterial two-component sHsp system. Alternative bacterial two-component small heat shock protein systems.,Bepperling A, Alte F, Kriehuber T, Braun N, Weinkauf S, Groll M, Haslbeck M, Buchner J Proc Natl Acad Sci U S A. 2012 Dec 11;109(50):20407-12. doi:, 10.1073/pnas.1209565109. Epub 2012 Nov 26. PMID:23184973[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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